Chapter 100

Peritonsillar Abscess

Erin A. Lyden

Definition and Epidemiology

A peritonsillar abscess (PTA) is an accumulation of pus within the peritonsillar tissues, between the tonsil and the pharyngeal constrictor muscle.¹^–³ PTA is a common deep infection of the head and neck.¹ The abscess frequently occurs in patients with a history of recurrent, chronic, or improperly treated tonsillitis.¹

Peritonsillar cellulitis and abscess formation are common occurrences in the middle teenage years through age 40.²^,⁴ The incidence rate for PTA varies internationally; one source lists 1 in 6500 in the United States and 1 in 10,000 in Northern Ireland.⁴ The incidence of PTAs reported is on the rise worldwide.² The recurrence of PTA is reported to be variable, from 9% to 22%.⁵ The risk of recurrence is higher if the patient is younger than 30 years and for patients who smoke.⁴

Specialist referral is recommended for PTA.

Pathophysiology

PTAs were previously believed to be a direct result of inadequately treated tonsillitis. The tonsillitis progresses to cellulitis, and eventually pus formation occurs in the peritonsillar tissue.²^,⁶ However, now there are two theories regarding the pathogenesis of PTAs.²^,⁶ One study found that 79% of patients reported symptoms of a sore throat before PTA, whereas another reported that 68% of the patients studied denied such symptoms before PTA diagnosis.² In addition to the theory that PTA is a complication of acute tonsillitis is the theory of blocked Weber glands.²^,⁶ These are salivary glands located on the upper soft palate.⁶ It has been suggested that infection secondary to poor oral hygiene or other sources (e.g., infections and smoking) could cause scarring that leads to an eventual blockage of the ducts of the Weber glands.² These glands are reported to assist in the removal of debris in the tonsil area. If these glands are obstructed by debris, inflammation, or pus, their function is impaired, contributing to the development of PTA.²^,⁶ PTA has been found to have both aerobic and anaerobic bacteria.¹

Clinical Presentation

The presentation typically consists of fever, chills, fatigue, malaise, foul breath, dysphagia, severe sore throat, and otalgia.⁶^,⁷ One small Canadian study noted that only 24% of patients had fever over 38° C.⁷ The patient may appear acutely ill and often reports pain radiating to the ear of the affected side. Trismus (spasms of the masticator muscles) is often noted. Drooling is typically present because of the inability to handle secretions. A “hot potato” (hoarse) voice is commonly noted.⁶

Physical Examination

With PTA, there is marked edema and erythema of the peritonsillar tissue and soft palate; this tissue is often fluctuant and covered with exudate.⁶ The findings are almost always unilateral, with the tonsil typically displaced downward and medially. The uvula is often edematous and displaced to the opposite side.⁷ Other findings include trismus, tender cervical adenopathy, tachycardia, pooling of saliva or drooling, and signs of dehydration.⁶ In a small study published in 2013, the patient’s physical examination revealed the “classic symptoms” of uvular deviation, trismus, and muffled voice in more than 90% of patients.⁷

Diagnostics

PTAs are easily diagnosed on the basis of physical findings. A computed tomography (CT) scan with contrast will confirm abscess formation and the presence of gas. Ultrasonography, either oral or cutaneous, in a cooperative, nonemergent patient can also be a useful diagnostic tool.¹

A complete blood count (CBC) often reveals leukocytosis.⁶^,⁷ A Monospot heterophile antibody test may be performed to exclude infectious mononucleosis.⁶ Culture and sensitivity testing of aspirate from the abscess typically reveals both aerobic and anaerobic bacteria.¹^,⁶^,⁷ Serum electrolytes may be ordered if the patient reports decreased oral intake. As with any other suspected infectious process, Gram stain and culture and sensitivity should be performed on any aspirated purulent material.¹